Ingredients
3 large eggs, room temperature
1/2 cup unbleached all-purpose flour
1/2 teaspoon kosher salt
3/4 cup whole milk, room temperature
2 scallions, light and dark green parts only, chopped
3 tablespoons unsalted butter, room temperature
Sliced smoked salmon, sour cream, and capers, for serving
Preparation
Preheat oven to 425°F, with a medium cast-iron skillet (10 inches, measured across top) inside on the center rack.
Purée eggs in a blender until pale and frothy, about 1 minute. Add flour, salt, and milk and purée until smooth, about 30 seconds (the batter will be thin). Add butter to skillet in oven. When it melts and sizzles, pull out the rack and quickly pour batter into center of skillet. Sprinkle top of batter evenly with scallions.
Bake until pancake is puffed, golden brown in places, and crisp along the edges, 18 to 22 minutes. Slice into wedges and serve immediately with salmon, sour cream, and capers.